Founded 2003 by Drew Sills and Doron Zeilberger.
Former co-organizers: Drew Sills (2003-2007), Moa ApaGodu (2005-2006), Lara Pudwell (2006-2008), Andrew Baxter (2008-2011), Brian Nakamura (2011-2013), Edinah Gnang (2011-2013), Matthew Russell (2013-2016), Nathan Fox (2016-2017), Bryan Ek (2017-2018), Mingjia Yang (2018-2020), Yonah Biers-Ariel (2018-2020), Robert Dougherty-Bliss (2020-2024), Stoyan Dimitrov (2023-2025)
Current co-organizers:
Doron Zeilberger (doronzeil {at} gmail [dot] com)
Aurora Hiveley (aurora.hiveley {at} scarletmail [dot] rutgers [dot] edu)
Lucy Martinez (lm1154 {at} scarletmail [dot] rutgers [dot] edu)
Archive of Previous Speakers and Talks You can find links to videos of some of these talks as well. Currently, our videos are being posted to our Vimeo page. Previously, we had videos posted on our YouTube page.
Date: Thu., March 5, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker:
Nayda Farnsworth , Colgate University
Title: A Computational Approach to Improving Bounds on the Hales-Jewett Numbers
Abstract: We use SAT solvers to improve bounds of the celebrated Hales-Jewett Numbers, one of the most important numbers in Ramsey Theory.
Date: Thu., March 12, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: Nathan Fox, Canisius University
Title: Counting Colored Trees
Abstract: A plane tree is a rooted tree where each node's children have a left-to-right order. Classically, the number of plane trees with n+1 vertices is equal to the nth Catalan number. We can generalize this basic enumeration problem to plane trees with colored vertices. We consider coloring rules that, given the color of the parent node, restrict the choices of how to color the children. This general framework is fertile ground for combinatorial exploration. For one thing, it generalizes many different examples that have been studied in the literature. It also leads to many new results, including bijections with other known problems. In this talk, we will explore various families of coloring rules and explore the integer sequences that enumerate plane trees colored according to those rules. This is joint work with Stoyan Dimitrov, Kimberly Hadaway, Ashley Tharp, and Stephan Wagner.
Date: Thu., March 19, 2026, 5:00pm (Eastern Time)
NO TALK (SPRING BREAK)
Date: Thu., March 26, 2026, 5:00pm (Eastern Time)
NO TALK, because of the dinner in honor of Natasha Ter-Saakov's defense, March 26, 2026. 10:30 am, Hill 482
Date: Thu., April 2, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker:
Victor Miller, Anduril Industries
Title: Summing a challenging series
Abstract: On the math-fun list, Neil Sloane posed the following problem: Let V(n) denote the integer formed by using the base 10 digits of n in base 11. It is classical that the series sum_n 1/V(n) converges. It is challenging to calculate a good approximation to its value. As a second, related, problem find a good approximation to the subseries sum_p 1/V(p), where the sum is over primes. It turned out that the first problem was efficiently solved by two related methods described by Robert Baillie and Jean-Francois Burnol. However, they do not appear to apply to the second sum, since they both depend, implicitly, on the fact that the language of digits in the first problem is a regular language, and a recent result of Thomas Dubbe shows, in a technical sense, that the digits of primes are poorly approximated by a regular language. In this talk I'll describe attempts at approximating the value of the second sum. They involve fractals, Fourier series, the prime zeta function, and the Karamata inequality. The process of analyzing this was helped, considerably, by experimentation, and seeing structure in graphs of quantities related to the series.
Date: Thu., April 9, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: tbd
Title: tbd
Abstract: tbd
Date: Thu., April 16, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: tbd
Title: tbd
Abstract: tbd
Date: Thu., April 23, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: tbd
Title: tbd
Abstract: tbd
Date: Thu., April 30, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: tbd
Title: tbd
Abstract: tbd
Date: Thu., May 7, 2026, 5:00pm (Eastern Time)
Zoom Link [password: The 20th Catalan number, alias (40)!/(20!*21!), alias 6564120420 ]
Speaker: Sergei Suslov, Arizona State University
Title: tbd
Abstract: tbd